Combine dry ingredients.
Separate egg yolk from white.
Whisk egg white to soft peaks.
Whisk egg yolk until color pales slightly.
Whisk dry ingredients, lemon juice, and honey into egg yolk.
Fold in egg whites, mixing gently, just until smooth.
Lightly grease a coffee cup and pour cake batter into cup.
Microwave on high for 2 minutes and 30 seconds.